The use of body insertion tubes, i.e., catheters that can be advanced (intubated) into a human body passage, is well-known. Of particular concern to the present invention are body insertion tubes which are configured either as endotracheal (ET) tubes or nasogastric (NG) tubes. ET tubes are catheter-like devices which are advanced through the mouth into a patient's pharynx and trachea to establish a pathway for ventilation to and from the lungs. NG tubes, on the other hand, are catheter-like devices which are advanced through the nose, pharynx, and esophagus to establish a pathway for fluid communication to and from the stomach, usually to aspirate stomach fluids.
In either case, areas of the body in opposition to the tube (e.g., the vocal cords, nasal passages, and epiglottis) are sensitive and can be irritated by the body insertion tube. Indeed, it can be appreciated that intubation can cause significant patient discomfort. Not only is the discomfort unpleasant for the patient, but it can induce involuntary reactions, such as muscle spasms, retching, etc., on the part of the patient. These involuntary reactions can understandably hinder ET tube or NG tube therapy and endanger the life of the patient.
Not surprisingly, devices have been introduced for anesthetizing portions of a body passage to reduce patient discomfort arising from catheter intubation. For example, U.S. Pat. No. 5,146,916 to Catalani discloses an ET tube that has a well-known inflatable cuff for establishing a fluid seal between the trachea and ET tube such that respiration can occur only through the ET tube. The Catalani invention includes a perforated cannula which extends along one side of the tube and which terminates in a perforated diffuser that surrounds the cuff, and anesthetic can be directed through the perforations to anesthetize portions of the trachea. Catalani also discloses an embodiment which has a small perforated diffuser cuff surrounding the ET tube proximal to the cuff.
Unfortunately, none of the Catalani devices as disclosed will, under all circumstances, completely anesthetize the more sensitive portions of the body passage into which the ET tube is positioned, namely the vocal cords and epiglottis which are ordinarily proximal to a properly placed cuff. More particularly, the perforated cannula of Catalani will not direct anesthetic onto the entire vocal cord/epiglottis region of a patient, but only onto the portion of the vocal cord/epiglottis region that directly faces the perforated cannula. Also, the small proximal diffuser cuff of Catalani is too narrow to ensure complete anesthetization of the vocal cord/epiglottis region, particularly given the positioning uncertainties inherent in ET tube use. In other words, the user of the Catalani device can unintentionally position the small diffuser cuff above or below the vocal cords, and thereby fail to ensure that anesthetic is directed onto the vocal cords.
In contrast to the Catalani device, U.S. Pat. No. 3,593,713 to Bogoff discloses a urethra catheter that has a tube with inflatable cuff for holding the tube within the urethra, and the Bogoff device includes a perforated jacket which encircles the tube. Anesthetic can be directed through the perforations to anesthetize portions of the urethra which are proximal to the cuff.
Unfortunately, the Bogoff device, like all urethra catheters, is unsuitable for ET and NG applications. Urethra catheters must be made of relatively pliant material, to avoid undue patient discomfort (particularly in males) when the device is in place. The pliancy of such catheters, however, would make them extremely difficult if not impossible to properly advance through a person's pharynx into the trachea or esophagus, particularly without the aid of a rigid positioning stylet, which may induce patient trauma, particularly when the catheter is advanced blindly as most NG tubes ordinarily are. This problem is particularly acute in NG applications, wherein the NG tube must be advanced through a person's nose, thereby obviating use of a styler altogether. Thus, urethra catheters do not have sufficient axial rigidity to permit them to be advanced into a patient's body passage through the pharynx. Also, urethra catheters are too short for NG tube applications.
Further, as recognized by the present invention, the pliant material from which urethra catheters must be made would tend to collapse when the lumen of the catheter is evacuated (e.g., in NG tube applications), or to unduly expand when the lumen is pressurized (e.g., in ET tube applications). Undue expansion of the lumen in ET tube applications is most undesirable, because the volume of oxygen actually provided to the patient (and not simply to expanding the ET tube) consequently cannot be reliably established. Collapse of the lumen in NG tube applications would prevent effective stomach suctioning.
Accordingly, the present invention recognizes the need to provide a body insertion tube which includes means for anesthetizing substantially all of the body passage in which the tube is intubated, which has axial rigidity sufficient to permit the tube to be advanced into a patient's body passage through the pharynx, and which will not collapse or expand under ET or NG application conditions.
It is accordingly an object of the present invention to provide a body insertion tube that has means for anesthetizing the body passage into which the tube is intubated. Another object of the present invention is to provide a body insertion tube which can easily be advanced into a body passage. Still another object of the present invention is to provide a body insertion tube which is easy to use, and cost-effective to manufacture.